U.S. patent application number 14/794947 was filed with the patent office on 2016-02-11 for etching method and method of manufacturing liquid discharge head substrate.
The applicant listed for this patent is CANON KABUSHIKI KAISHA. Invention is credited to Hisanori Hosaka, Yuzuru Ishida, Toshiyasu Sakai, Takashi Usui.
Application Number | 20160039206 14/794947 |
Document ID | / |
Family ID | 55266758 |
Filed Date | 2016-02-11 |
United States Patent
Application |
20160039206 |
Kind Code |
A1 |
Usui; Takashi ; et
al. |
February 11, 2016 |
ETCHING METHOD AND METHOD OF MANUFACTURING LIQUID DISCHARGE HEAD
SUBSTRATE
Abstract
An etching method of etching a first member containing iridium
is provided. The method includes forming a second member above the
first member, forming a first mask pattern on the second member,
forming a second mask pattern by etching the second member using
the first mask pattern and etching the first member using the first
mask pattern and the second mask pattern. In etching the first
member, the first member is etched on a condition that the first
mask pattern shrinks and an upper surface of the second mask
pattern is partially exposed.
Inventors: |
Usui; Takashi;
(Ashigarakami-gun, JP) ; Sakai; Toshiyasu;
(Kawasaki-shi, JP) ; Ishida; Yuzuru;
(Yokohama-shi, JP) ; Hosaka; Hisanori; (Oita-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CANON KABUSHIKI KAISHA |
Tokyo |
|
JP |
|
|
Family ID: |
55266758 |
Appl. No.: |
14/794947 |
Filed: |
July 9, 2015 |
Current U.S.
Class: |
438/21 ; 216/41;
216/49; 216/51 |
Current CPC
Class: |
B41J 2/1629 20130101;
B41J 2/1631 20130101; B41J 2/1642 20130101; B41J 2/14129 20130101;
B41J 2/1603 20130101; B41J 2/1646 20130101; B41J 2/1628
20130101 |
International
Class: |
B41J 2/16 20060101
B41J002/16 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 6, 2014 |
JP |
2014-160797 |
Claims
1. An etching method of etching a first member containing iridium,
the method comprising: forming a second member above the first
member; forming a first mask pattern on the second member; forming
a second mask pattern by etching the second member using the first
mask pattern; and etching the first member using the first mask
pattern and the second mask pattern, wherein in etching the first
member, the first member is etched on a condition that the first
mask pattern shrinks and an upper surface of the second mask
pattern is partially exposed.
2. The method according to claim 1, wherein at an end of etching
the first member, an entire upper surface of a pattern of the first
member is covered with the second mask pattern.
3. The method according to claim 1, wherein O.sub.2 gas is
contained in a processing gas used in etching the first member.
4. The method according to claim 1, wherein a material of the
second member includes an inorganic material.
5. The method according to claim 4, wherein the material of the
second member includes an inorganic material other than a
metal.
6. The method according to claim 4, wherein the material of the
second member is SiO.sub.2.
7. The method according to claim 1, wherein a material of the first
mask pattern includes an organic material.
8. A method of manufacturing a liquid discharge head substrate, the
method comprising: forming, above a substrate where a semiconductor
element is arranged, an element configured to generate energy to be
used in discharging a liquid; forming, above the element, a first
member containing iridium; forming a second member above the first
member; forming a first mask pattern on the second member; forming
a second mask pattern by etching the second member using the first
mask pattern; and etching the first member using the first mask
pattern and the second mask pattern, wherein in etching the first
member, the first member is etched on a condition that the first
mask pattern shrinks and an upper surface of the second mask
pattern is partially exposed.
9. The method according to claim 8, further comprising forming a
first protection layer above the element before forming the first
member, wherein the method includes etching the first protection
layer by using the first mask pattern and the second mask
pattern.
10. The method according to claim 8, further comprising forming a
second protection layer on the first member before forming the
second member, wherein the method includes etching the second
protection layer by using the first mask pattern.
11. The method according to claim 9, wherein the first protection
layer is formed from tantalum.
12. The method according to claim 10, wherein the second protection
layer is formed from tantalum.
13. The method according to claim 9, further comprising forming a
second protection layer on the first member before forming the
second member, wherein the method includes etching the second
protection layer by using the first mask pattern, and a sum of a
thickness of the first protection layer and a thickness of the
first member is smaller than a thickness of the second protection
layer.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an etching method and a
method of manufacturing a liquid discharge head substrate.
[0003] 2. Description of the Related Art
[0004] A liquid discharge head substrate includes a portion which
applies energy to a liquid to discharge the liquid and a protection
layer for protecting the portion from the shock of cavitation
caused when the liquid generates bubbles. Japanese Patent Laid-Open
No. 2012-183681 describes that a stacked structure containing
iridium is used as the protection layer. As a result, the
anti-cavitation capability of the protection layer improves.
Furthermore, Japanese Patent Laid-Open No. 2000-133783 describes a
method of retreating the side wall of a resist mask by using a
processing gas obtained by adding oxygen to chlorine gas when
patterning an iridium layer by dry etching using the resist mask.
As a result, a reaction product which adheres to the side wall of a
pattern is removed, and a highly accurate and fine pattern of the
iridium layer can be formed.
SUMMARY OF THE INVENTION
[0005] When etching the iridium layer by a method described in
Japanese Patent Laid-Open No. 2000-133783, the side surface of a
resist mask on the iridium layer retreats, and thus the end portion
of the upper surface of the iridium layer may be exposed. The
present inventors have found that this exposed portion may be
roughened greatly if it is exposed to a plasma used in the etching
process. In this case, the upper surface of the iridium layer
locally includes a greatly roughened portion after removing the
resist mask. If the method described in Japanese Patent Laid-Open
No. 2000-133783 is used to form a structure described in Japanese
Patent Laid-Open No. 2012-183681, another film is deposited on the
iridium layer having such an upper surface. As a result, for
example, the adhesion between this film and the iridium layer may
degrade, resulting in peeling off the film. Some embodiments of the
present invention provide a technique of reducing the roughness of
a member containing iridium caused when etching the member.
[0006] According to some embodiments, an etching method of etching
a first member containing iridium, the method comprising: forming a
second member above the first member; forming a first mask pattern
on the second member; forming a second mask pattern by etching the
second member using the first mask pattern; and etching the first
member using the first mask pattern and the second mask pattern,
wherein in etching the first member, the first member is etched on
a condition that the first mask pattern shrinks and an upper
surface of the second mask pattern is partially exposed, is
provided.
[0007] According to some other embodiments, a method of
manufacturing a liquid discharge head substrate, the method
comprising: forming, above a substrate where a semiconductor
element is arranged, an element configured to generate energy to be
used in discharging a liquid; forming, above the element, a first
member containing iridium; forming a second member above the first
member; forming a first mask pattern on the second member; forming
a second mask pattern by etching the second member using the first
mask pattern; and etching the first member using the first mask
pattern and the second mask pattern, wherein in etching the first
member, the first member is etched on a condition that the first
mask pattern shrinks and an upper surface of the second mask
pattern is partially exposed, is provide.
[0008] Further features of the present invention will become
apparent from the following description of exemplary embodiments
(with reference to the attached drawings).
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a partially cutaway perspective view showing a
liquid discharge head substrate according to an embodiment of the
present invention;
[0010] FIG. 2 is a sectional view showing the liquid discharge head
substrate in FIG. 1;
[0011] FIGS. 3A to 3E are sectional views showing the steps in a
method of manufacturing the liquid discharge head substrate in FIG.
1;
[0012] FIG. 4 is a sectional view showing a liquid discharge head
substrate according to an embodiment of the present invention;
and
[0013] FIG. 5 is a sectional view showing a liquid discharge head
substrate according to an embodiment of the present invention.
DESCRIPTION OF THE EMBODIMENTS
[0014] Practical embodiments of an etching method and a method of
manufacturing a semiconductor device according to the present
invention will be described below. In the following embodiments, a
liquid discharge head substrate is used as an example of the
semiconductor device. However, the present invention is not limited
to this.
[0015] The structure of the liquid discharge head substrate
according to some embodiments of the present invention will be
described with reference to FIGS. 1 and 2. FIG. 1 is a partially
cutaway perspective view schematically showing an example of the
arrangement of a liquid discharge head substrate 100 according to a
first embodiment of the present invention. The liquid discharge
head substrate 100 according to this embodiment includes a
plurality of heaters 102 on a substrate 101 where a liquid supply
port 113 having a long groove-shaped through-hole to supply a
liquid such as ink is open. A channel member which forms a channel
(not shown) through which the liquid flows and a plate 114 where an
orifice 109 corresponding to each heater 102 is provided are formed
on the substrate 101, thereby forming the liquid discharge head
substrate 100. If the liquid is supplied from the liquid supply
port 113 to the channel, each heater 102 provided in the channel
applies thermal energy to the liquid and the liquid is discharged
from the corresponding orifice 109 by a bubble generated in the
liquid.
[0016] FIG. 2 is a sectional view schematically showing an example
of the arrangement of the periphery of one heater of the liquid
discharge head substrate 100 according to this embodiment. The
heater 102 which generates heat by being energized is provided on
the substrate 101. A wiring layer 203 for supplying power to the
heater 102 is provided on this heater 102. Furthermore, an
insulating layer 204 is provided on the substrate 101 so as to
cover the heater 102 and the wiring layer 203. A protection layer
202 for protecting the heater 102 from the shock of cavitation
caused when generating the bubble is provided in a region facing
the heater 102 on the insulating layer 204. The protection layer
202 may also be called an anti-cavitation layer. In this
embodiment, the protection layer 202 is formed by three layers of a
lower protection layer 205 serving as the first protection layer,
an iridium layer 206 formed from iridium serving as the first
member, and an upper protection layer 207 serving as the second
protection layer. A hard mask layer 208 serving as the second
member is provided on the protection layer 202. The plate 114
including the orifice 109 is provided spaced above these
structures.
[0017] A method of manufacturing the above-described liquid
discharge head substrate 100 according to this embodiment will now
be described with reference to FIGS. 3A to 3E. A material such as
TaSiN is deposited, by using a sputtering method or the like, with
the thickness of, for example, 20 nm on the substrate 101 where a
driving circuit (not shown) including a semiconductor element such
as a switching transistor configured to drive the heater 102
selectively is formed. Next, a material such as an Al--Cu based
alloy is deposited, by using the sputtering method or the like,
with the thickness of, for example, 600 nm. Then, the film of the
Al--Cu based alloy is etched by performing a photolithography
process and dry etching using a processing gas such as Cl.sub.2
gas, thereby forming the wiring layer 203. After that, the film of
TaSiN is etched by performing the photolithography process and wet
etching using a mixed acid, thereby forming the heater 102.
[0018] Then, the insulating layer 204 is formed, by using CVD
method or the like, on the substrate 101 so as to cover the heater
102 and the wiring layer 203. In this embodiment, the insulating
layer 204 is formed from SiN and has the thickness of, for example,
300 nm. Note that the insulating layer 204 suffices to be able to
insulate the heater 102 and the wiring layer 203 from the liquid,
and may use an insulating material such as SiO, SiC, or SiCN. FIG.
3A shows a section after the end of this step.
[0019] Next, the protection layer 202 for protecting the heater 102
from cavitation caused when a bubble generated at the time of
liquid discharge disappears is formed on the insulating layer 204.
In this embodiment, the protection layer 202 is formed by the three
layers, and forms, by using the sputtering method or the like,
20-nm tantalum as the lower protection layer 205, the 40-nm iridium
layer 206, and 100-nm tantalum as the upper protection layer 207,
respectively. In this embodiment, the sum of film thicknesses of
the lower protection layer 205 and the iridium layer 206 is smaller
than the film thickness of the upper protection layer 207. Note
that the lower protection layer 205 suffices to have a film
thickness capable of ensuring the adhesion between the insulating
layer 204 and the iridium layer 206. The lower protection layer 205
is formed to have the thickness of, for example, 5 nm to 100 nm.
The iridium layer 206 is formed to have a thickness that can endure
the shock of cavitation to be generated of the number of discharge
operations required for the liquid discharge head. The iridium
layer 206 is formed to have the thickness of, for example, 10 nm to
100 nm. The upper protection layer 207 has a thickness that can
sufficiently cover the iridium layer 206. The upper protection
layer 207 is formed to have a thickness of, for example, 30 nm to
200 nm. Note that the upper protection layer 207 has a function of
preventing a burn from physically adsorbing to the surface of the
iridium layer 206. The burn refers to a hardly soluble substance
obtained by decomposing, at the molecular level, a color material
and an additive contained in ink in high-temperature heating.
Droplet discharge may become unstable if the burn adheres to a film
surface.
[0020] Further, as shown in FIG. 3B, the hard mask layer 208
serving as the second member is formed, by using CVD method, on the
upper protection layer 207. For example, an inorganic material
other than a metal is used for the hard mask layer 208. In this
embodiment, SiO.sub.2 is used to form the hard mask layer 208 with
the thickness of 100 nm. If the film thickness of the hard mask
layer 208 is large, pattern formation becomes difficult when
etching is performed in the next step to form the second mask
pattern. The hard mask layer 208 does not function as a hard mask
if its film thickness is small.
[0021] Then, as shown in FIG. 3C, a first mask pattern 209 is
formed on the hard mask layer 208. The first mask pattern 209
covers at least a portion of the heater 102 that should be
protected from cavitation and has openings in other portions. In
this embodiment, a photoresist made of an organic material is used
as a material for the first mask pattern. The photoresist is coated
onto the substrate 101 covered with the hard mask layer 208, and
desired patterning is performed by an exposure device, thereby
forming the first mask pattern 209. In this case, the thickness of
a photoresist film is about, for example, 2.5 .mu.m. The film
thickness of this photoresist suffices to have an adequate
resistance as a mask when etching the hard mask layer 208.
[0022] Subsequently, the hard mask layer 208 is etched to form the
second mask pattern, and the protection layer 202 formed by the
three layers is also etched. More specifically, first, by a dry
etching method or the like using the first mask pattern 209, the
portion of the hard mask layer 208 and the upper protection layer
207 lying under the opening portion of the first mask pattern 209
is etched. In this embodiment, processing gases such as Cl.sub.2
gas and BCl.sub.3 gas are introduced into a reaction chamber where
etching is performed, and a pressure in the reaction chamber is
controlled to be 1.33 Pa (10 mTorr) to 2.67 Pa (20 mTorr). After
the reaction chamber is stabilized, a high-frequency power of 13.56
MHz is applied to the upper part and the lower part of the
electrode of the reaction chamber, thereby generating a plasma and
performing etching. In this case, while the first mask pattern 209
is etched slightly, the hard mask layer 208 and the upper
protection layer 207 are etched faster than the first mask pattern
209. Therefore, no step is formed in each side wall between the
first mask pattern 209, and the hard mask layer 208 and the upper
protection layer 207. FIG. 3D shows a section after the end of this
step.
[0023] Next, the iridium layer 206 is etched, by using the dry
etching method or the like, through the opening portion of the
first mask pattern 209 and the hard mask layer 208 where the second
mask pattern are formed. Processing gases such as Cl.sub.2 gas,
O.sub.2 gas, and Ar are introduced into the reaction chamber where
etching is performed, and the pressure in the reaction chamber is
controlled to be 0.667 Pa (5 mTorr) to 1.33 Pa (10 mTorr). After
the reaction chamber is stabilized, the high-frequency power of
13.56 MHz is applied to the upper electrode and the lower electrode
of the reaction chamber, thereby generating a plasma and performing
etching.
[0024] Since O.sub.2 gas is added to, or contained in, the
processing gases, an etching reaction proceeds faster in the first
mask pattern 209 formed by the organic material than in the hard
mask layer 208. Therefore, the area of the first mask pattern 209
covering the hard mask layer 208 is reduced, or shrinks. More
specifically, each side surface of the first mask pattern 209
retreats by about 1 to 2 .mu.m with respect to the corresponding
side surface of the hard mask layer 208, partially exposing the
upper surface of the hard mask layer 208. Furthermore, since
etching proceeds while cutting each side surface of the first mask
pattern 209, iridium deposits adhering to the side surface of the
first mask pattern 209 can be reduced. This makes it possible to
suppress a separation failure caused in a separation processing
step of separating these deposits and increase a manufacturing
yield. Furthermore, since O.sub.2 gas is added to the processing
gases, tantalum oxide is generated on the surface of the lower
protection layer 205 lying under the iridium layer 206. As a
result, etching is less likely to proceed on the surface of the
lower protection layer 205, and an effect of increasing selectivity
between the lower protection layer 205 and the iridium layer 206 is
also obtained.
[0025] Next, the lower protection layer 205 is etched by using the
second mask pattern formed by the hard mask layer 208. An etching
condition in this case can be the same as a condition when etching
the upper protection layer 207. Further, for example, the pressure
in the reaction chamber may be controlled to be high so as not to
etch the insulating layer 204 under the lower protection layer 205.
Furthermore, the processing gases may be changed. FIG. 3E shows a
section after the end of this step. A nozzle material film (not
shown) is formed after forming this protection layer.
[0026] The effect of this embodiment will now be described. If the
manufacturing method described in Japanese Patent Laid-Open No.
2000-133783 is applied to etch the iridium layer, etching of the
photoresist made of the organic material proceeds and the
photoresist is retreated further than the formed mask pattern
because O.sub.2 gas is added to the processing gases for etching.
If this is applied to the arrangement of the liquid discharge head
substrate described in Japanese Patent Laid-Open No. 2012-183681,
the end portion of the iridium layer exposed when being etched is
exposed to a plasma in an etching process. The upper surface of the
iridium layer exposed to a plasma in this etching process may be
roughened locally and greatly. If a film is deposited on such a
locally roughened iridium layer in the succeeding steps, the
adhesion of the film may degrade, resulting in peeling of the
film.
[0027] In this embodiment, the hard mask layer 208 is difficult to
etch in the etching process of the iridium layer 206. Therefore,
roughness that may cause trouble in steps after the formation of
the protection layer does not occur on the upper surface of the
hard mask layer 208. Since the hard mask layer 208 exists, at the
end of etching, on the entire upper surfaces of the upper
protection layer 207 and the iridium layer 206 under the hard mask
layer 208, it is not exposed to a plasma in the etching process.
This suppresses the problem of film peeling caused by degradation
in the adhesion of the film deposited on the hard mask layer 208 in
the steps after the formation of the protection layer. As a result,
the manufacturing yield is increased.
[0028] After that, the plate 114 including the orifices 109 is
formed. These arrangements can be formed by using an existing
method, and thus a detailed description thereof will be omitted.
The liquid discharge head substrate 100 shown in FIGS. 1 and 2 is
formed by the above-described process.
[0029] The structure of a liquid discharge head substrate 400
according to a second embodiment of the present invention will be
described with reference to FIG. 4. FIG. 4 is a sectional view
schematically showing an example of the arrangement of the
periphery of one heater of the liquid discharge head substrate 400
according to the second embodiment of the present invention. The
liquid discharge head substrate 400 according to this embodiment in
FIG. 4 can be the same as the liquid discharge head substrate 100
according to the first embodiment except that it does not include
an upper protection layer 207 in a protection layer 402. Therefore,
a repetitive description on the same components as those of the
liquid discharge head substrate 100 will be omitted.
[0030] A method of manufacturing the liquid discharge head
substrate 400 will now be described. The method according to this
embodiment is the same as the method of manufacturing the liquid
discharge head substrate 100 up to a step of forming an iridium
layer 206. After forming the iridium layer 206, a hard mask layer
208 is formed by using CVD method or the like. Then, a first mask
pattern 209 is formed on the hard mask layer 208. Next, the portion
of the hard mask layer 208 lying under the opening portion of the
first mask pattern 209 is etched by using a dry etching method or
the like, thereby forming the second mask pattern. In this case,
while the first mask pattern 209 is etched slightly, the hard mask
layer 208 is etched faster than the first mask pattern 209.
Therefore, no step is formed in each side wall between the hard
mask layer 208 and the first mask pattern 209.
[0031] Next, the portion of the iridium layer 206 lying under the
opening portion of the first mask pattern 209 and the hard mask
layer 208 where the second mask pattern are formed is etched by
using the dry etching method or the like. Next, a lower protection
layer 205 is etched by using the second mask pattern formed by the
hard mask layer 208, thereby forming the protection layer 402.
After forming this protection layer 402, the liquid discharge head
substrate 400 is formed by the same process as in the method of
manufacturing the liquid discharge head substrate 100.
[0032] Also in this embodiment, no roughness occurs on the upper
surface of the hard mask layer 208 in a step of etching the iridium
layer 206 and the lower protection layer 205. Since the hard mask
layer 208 exists on the iridium layer 206 at the end of etching,
the upper surface of the iridium layer 206 is not exposed to a
plasma in an etching process. Therefore, the same effect as in the
method of manufacturing the liquid discharge head substrate 100
described in the first embodiment can also be obtained in the
method of manufacturing the liquid discharge head substrate 400
according to this embodiment.
[0033] The structure of a liquid discharge head substrate 500
according to a third embodiment of the present invention will be
described with reference to FIG. 5. FIG. 5 is a sectional view
schematically showing an example of the arrangement of the
periphery of one heater of the liquid discharge head substrate 500
according to the third embodiment of the present invention. The
liquid discharge head substrate 500 according to this embodiment in
FIG. 5 can be the same as the liquid discharge head substrates 100
and 400 according to the first and second embodiments except that
it includes only an iridium layer 206 in a protection layer 502.
Therefore, a repetitive description on the same components as those
of the liquid discharge head substrate 400 will be omitted.
[0034] A method of manufacturing the liquid discharge head
substrate 500 will now be described. The method according to this
embodiment is the same as the method of manufacturing each of the
liquid discharge head substrates 100 and 400 up to a step of
forming an insulating layer 204. After forming the insulating layer
204, the iridium layer 206 is formed by using a sputtering method
or the like, and a hard mask layer 208 is further formed on the
iridium layer 206 by using CVD method or the like. Then, a first
mask pattern 209 is formed on the hard mask layer 208. Next, the
portion of the hard mask layer 208 lying under the opening portion
of the first mask pattern 209 is etched by using a dry etching
method or the like, thereby forming the second mask pattern. In
this case, while the first mask pattern 209 is etched slightly, the
hard mask layer 208 is etched faster than the first mask pattern
209. Therefore, no step is formed in each side wall between the
hard mask layer 208 and the first mask pattern 209.
[0035] Next, the portion of the iridium layer 206 lying under the
opening portion of the first mask pattern 209 and the hard mask
layer 208 where the second mask pattern are formed is etched by
using the dry etching method or the like, thereby forming the
protection layer. After forming this protection layer, the liquid
discharge head substrate 500 is formed by the same process as in
the method of manufacturing each of the liquid discharge head
substrates 100 and 400.
[0036] Also in this embodiment, no roughness occurs on the upper
surface of the hard mask layer 208 in this etching step. Since the
hard mask layer 208 exists on the iridium layer 206 at the end of
etching, the upper surface of the iridium layer 206 is not exposed
to a plasma in an etching process. Therefore, the same effect as in
the method of manufacturing each of the liquid discharge head
substrates 100 and 400 described in the first and second
embodiments can also be obtained in the method of manufacturing the
liquid discharge head substrate 500.
[0037] The three embodiments according to the present invention
have been described above. However, the present invention is not
limited to these embodiments. The present invention may be applied
to, for example, a liquid discharge head substrate which discharges
a liquid by applying, using a piezoelectric element or the like, a
mechanical force to the liquid. Further, an etching method of the
present invention can also be applied to a method of manufacturing
another semiconductor device, such as a storage device or an
arithmetic processing device.
[0038] While the present invention has been described with
reference to exemplary embodiments, it is to be understood that the
invention is not limited to the disclosed exemplary embodiments.
The scope of the following claims is to be accorded the broadest
interpretation so as to encompass all such modifications and
equivalent structures and functions.
[0039] This application claims the benefit of Japanese Patent
Application No. 2014-160797, filed Aug. 6, 2014, which is hereby
incorporated by reference wherein in its entirety.
* * * * *